In medicine, a prosthesis (from Ancient Greek prosthesis, “addition, application, attachment”) is an artificial device that replaces a missing body part, which may be lost through trauma, disease, or congenital conditions.
Limb prostheses include both upper- and lower-extremity prostheses. Upper-extremity prostheses are used at varying levels of amputation: forequarter, shoulder disarticulation, transhumeral prosthesis, elbow disarticulation, transradial prosthesis, wrist disarticulation, full hand, partial hand, finger, partial finger.
Lower-extremity prostheses provide replacements at varying levels of amputation. These include hip disarticulation, transfemoral prosthesis, knee disarticulation, transtibial prosthesis, Syme's amputation, foot, partial foot, and toe. The two main subcategories of lower extremity prosthetic devices are trans-tibial (any amputation transecting the tibia bone or a congenital anomaly resulting in a tibial deficiency) and trans-femoral (any amputation transecting the femur bone or a congenital anomaly resulting in a femoral deficiency).
A transfemoral prosthesis is an artificial limb that replaces a leg missing above the knee. Transfemoral amputees can have a very difficult time regaining normal movement. In general, a transfemoral amputee must use approximately 80% more energy to walk than a person with two whole legs. This is due to the complexities in movement associated with the knee. In newer and more improved designs, hydraulics, carbon fiber, mechanical linkages, motors, computer microprocessors, and innovative combinations of these technologies are employed to give more control to the user. In the prosthetic industry, a trans-femoral prosthetic leg is often referred to as an “AK” or above the knee prosthesis.
A transtibial prosthesis is an artificial limb that replaces a leg missing below the knee. A transtibial amputee is usually able to regain normal movement more readily than someone with a transfemoral amputation, due in large part to retaining the knee, which allows for easier movement. Lower extremity prosthetics describes artificially replaced limbs located at the hip level or lower. In the prosthetic industry, a trans-tibial prosthetic leg is often referred to as a “BK” or below the knee prosthesis.
Over the years, there have been advancements in artificial limbs. New plastics and other materials, such as carbon fiber, have allowed artificial limbs to be stronger and lighter, limiting the amount of extra energy necessary to operate the limb. This is especially important for trans-femoral amputees. Additional materials have allowed some artificial limbs to look much more realistic, which is important to trans-radial and transhumeral amputees because they are more likely to have the artificial limb exposed.
In addition to new materials, the use of electronics has become very common in artificial limbs.
Myoelectric limbs, which control the limbs by converting muscle movements to electrical signals, have become much more common than cable operated limbs. Myoelectric signals are picked up by electrodes, the signal gets integrated and once it exceeds a certain threshold, the prosthetic limb control signal is triggered which is why inherently, all myoelectric controls lag. Conversely, cable control is immediate and physical, and through that offers a certain degree of direct force feedback that myoelectric control does not.
Computers are also used extensively in the manufacturing of limbs. Computer Aided Design and Computer Aided Manufacturing are often used to assist in the design and manufacture of artificial limbs.
Most modern artificial limbs are attached to the stump of the amputee by belts and cuffs or by suction. The stump either directly fits into a socket on the prosthetic, or-more commonly today-a liner is used that then is fixed to the socket either by vacuum (suction sockets) or a pin lock. Liners are soft and by that, they can create a far better suction fit than hard sockets.
Silicone liners can be obtained in standard sizes, mostly with a circular (round) cross section, but for any other stump shape, custom liners can be made. The socket is custom made to fit the residual limb and to distribute the forces of the artificial limb across the area of the stump (rather than just one small spot), which helps reduce wear on the stump. The custom socket is created by taking a plaster cast of the stump or, more commonly today, of the liner worn over the stump, and then making a mold from the plaster cast.
Newer methods include laser guided measuring which can be input directly to a computer allowing for a more sophisticated design.
Cosmetic prosthesis has long been used to disguise injuries and disfigurements. With advances in modern technology, cosmesis, the creation of lifelike limbs made from silicone or PVC has been made possible. Such prosthetics, including artificial hands, can now be designed to simulate the appearance of real hands, complete with freckles, veins, hair, fingerprints and even tattoos.
Custom-made cosmeses are generally more expensive (costing thousands of U.S. dollars, depending on the level of detail), while standard cosmeses come premade in a variety of sizes, although they are often not as realistic as their custom-made counterparts. One option is the custom-made silicone cover, which can be made to match a person's skin tone but not details such as freckles or wrinkles.
Cosmeses are typically attached to the body in any number of ways, using an adhesive, suction, form-fitting, stretchable skin, or a skin sleeve. These devices can be difficult to use, time consuming, and unwieldly.
It is desirable for prosthetic users to utilize some type of prosthetic cover to hide the prosthetic mechanism and provide a smooth limb like surface for supporting clothing. Covers also provide the aesthetic look and feel of a natural limb. The cover allows the user to look and feel like a “normal” person which can have the effect of boosting the user's self-confidence and self-esteem.
Existing prosthesis covers can be bulky and cumbersome. Some covers require the use of screws, buckles, straps, or tools to install or uninstall the covers on a prosthesis.
Some prosthetic covers require complex or tedious fitting operations to ensure the cover fits the prosthesis, such as a lower leg. While still other designs require custom fitting for each user, which can be very costly and time consuming.
For example, U.S. Pat. No. 5,593,453 to Alhert, discloses prosthesis cover formed of waterproof sheet material having leg and foot portions, the foot portion having sole, toe and heel portions and side marginal edges between the toe and sole on both sides of the cover, an antiskid surface covering the foot portion, an open top end, the leg portion having a frusto-conical top segment for engagement with the prosthesis at the top end of the cover, finger loops positioned behind the heel and on opposite sides of the leg portion just below the open top, the leg and foot portions having contours and shape closely conforming to the shape of the prosthesis being covered, and a plurality of inwardly directed ribs being formed on the inner surface of the leg portion of the cover, the plurality of ribs being spaced apart from each other with each rib extending concentrically of the leg portion, the plurality of ribs extending along said inner surface from just above an ankle portion throughout the height of the leg portion to just below the top segment, so that the plurality of ribs spaces the inner cover surface from the prosthesis thereby to reduce frictional engagement when the cover is being applied by sliding over the prosthesis, and so that when the cover is in place the ribs engage the prosthesis and prevent the cover from slipping down along the prosthesis during use.
Thus, it is desirable for a prosthetic cover to include features for easily adjusting to a range of user sizes or lengths while being able to be removably installed or uninstalled quickly and efficiently without the use of screws, buckles, straps, or tools and the like.
The present invention provides novel devices, systems, and methods for improving the ease of use and flexibility of fitting, installing, and uninstalling, prosthetic covers and cover systems.